Pipes, especially relatively small diameter copper pipes between one half inch and two inches nominal diameter, are used extensively to provide water service for homes, business and industry. Such pipes may be healingly joined to one another end to end using mechanical couplings to create a piping network for conveying water throughout a building such as a home, office or factory.
Mechanical couplings provide various advantages over traditional solder joints for connecting pipes in that they avoid the use of acid flux, solder and open flame to effect a connection. Assembly of a joint using a mechanical coupling also requires less time than a solder joint and may be performed by a less skilled worker. Assembly of a joint merely requires that a pipe end be inserted into a coupling so that the coupling and pipe end engage properly.
The mechanical coupling, which may be a fitting such as an elbow, tee or straight fitting, for example, includes a housing having a socket coaxially aligned with a receptacle for receiving the pipe end. A sealing member, such as an O-ring or a pressure responsive seal and a retainer are captured within the receptacle adjacent to the socket. The retainer may have a plurality of flexible teeth that extend around the circumference of the receptacle. The teeth project radically inwardly and are angularly oriented toward the socket. When the pipe end is inserted through the receptacle and into the socket, the teeth engage the pipe's outer surface and retain it within the coupling. Due to their angular orientation, the teeth are “self jamming” and resist motion of the pipe that would tend to force it from the receptacle. The sealing member within the receptacle engages the pipe and the housing to provide a fluid-tight seal, and the socket supports the pipe and provides bending stiffness to the joint, preventing angular deflection between the pipe and the coupling.
To obtain the advantages associated with a mechanical coupling and ensure an effective, fluid-tight joint, the pipe end must seat properly within the coupling. It must be insert able smoothly without causing damage to the sealing member or the retainer and must engage the socket over the proper engagement length so that the joint is secure and fluid tight. To this end it is found advantageous to chamfer the pipe end. Chamfering removes any burrs which could cut the sealing member or interfere with insertion of the pipe into the close-fitting socket. Chamfering also creates a smooth, tapered surface that facilitates insertion of the pipe end into the coupling, helping the pipe to align itself co-axially, more easily deflect retainer teeth, more easily radically compress the seal, and more easily enter the socket.
While there are many tools that chamfer pipe, they suffer from various disadvantages. They tend to be complicated and expensive, and they do not reliably cut uniform chamfers because it is difficult for the technician to maintain proper concentricity between the pipe and the tool and keep the pipe co-axial with the tool. With such tools there is furthermore no way to identify when the formation of the chamfer is complete without removing the tool from the pipe. There is clearly a need for an improved chamfering tool for pipe preparation, especially for use with mechanical fittings.